Fuel oil compositions containing antimicrobial agents



United States Patent FUEL OIL COMPOSITIONS CONTAINING ANTIMICROBIAL AGENTS Gulf Oil Corporation, Pittsburgh, Pa., a corporation of Pennsylvania No Drawing. Filed Sept. 29, 1955, Ser. No. 537,585

' 9 Claims. 01. 44-56) This invention relates to fuel oil compositions containing anti-microbial agents, and more particularly to fuel oil compositions that tend to deposit gels derived from gel-forming microorganisms, and that contain a small amount of an anti-microbial agent effective to destroy said gel-forming microorganisms. The invention also includes methods of treating fuel oils of the type described in order to reduce gel deposition.

Numerous East Coast marketers of distillate fuel oils have recently received increasing numbers of complaints because of malfunctioning of distillate fuel oil burners due to accumulations of gelatinous deposits in fuel lines, strainers, burner. nozzles, filters, needle valves, level controls, and the like. In numerous instances physical removal of the gelatinous deposits has failed to provide more than temporary relief, with the result that further service calls have been necessary to remove additional gel deposits, often within as short a time as 7 days or less. Thus, many burner installations show..a history of repeated serivce calls due to gel deposits within the course of a single heating season.

- As an indication of the seriousness of this problem it may be mentioned that a recent survey of distillate fuel oil burner installations in a region where complaints due to gel deposition have been received in the past deposits and because of their persistence in the face of ordinary methods used to combat fuel oil deposits such as sludge, and because of other factors, it was recognized thatthe problem of fuel oil gels was new and distinct from previous problems of distillate fuel oil deposits.

Systematic attempts to trace the cause of fuel oil gel deposits to an entirely chemical source, such as for example,.chemical impurities, degradation or decomposition of one or more of the petroleum components of the fuel oils, or to chemical additives included in the fuel oil to improve one or more of its properties, have not been successful.

It has now been found that these fuel oil gels are of microbial derivation, and that they are due to the presence of gel-forming microorganisms in the fuel oil as such and/or in water entrained by or contacted by the fuel oil. It has further been found that the problem of gel deposition in distillate fuel oils that normally tend to deposit gels can be greatly alleviated by treating the oils with a small amount of an anti-microbial agent that is effective to kill said fuel oil gel-forming microoganisms. The present invention therefore includes fuel oil compositions which comprise a major proportion of a distillate fuel oil that normally tends to deposit gels due to the presence of gel-forming microorganisms, and a micro ,bicidal proportion of an anti-microbial agent that is effective to kill the fuel oil gel-forming microorganisms.

The invention also includes treatment of distillate fuel Claude R. Summers, Jr., Havertown, Pa., assignor to ice oils of the kind described with anti-microbial agents to reduce gel deposition.

The fuel oil gels with which this invention is concerned have been found to occur mostly in the form of beads and films. Occasionally, however, the gel deposits are in fibrous form. When in relatively pure form the fuel oil gels have been found to be clear and generally yellowish in color, but these characteristics are sometimes masked by contamination of the gel with black fuel oil sludge or other minute particles of debris normally present in the fuel oil.

Chemical analysis of a large number of samples of these fuel oil gels shows that they all contain significant proportions of water, sulfur and copper. Where the fuel oils contain chemical addition agents, such as for example sludge inhibitors, appreciable proportions of chemical components traceable to these additives, or the additives themselves, may be found in the gels. By way of illustrating the chemical composition of these gels there are presented below analytical data on two samples of fuel oil gels removed from different burner installations. In both instances the gel as such was separated from concomitant fuel oil and sediment by heating the crude sample originally removed from the burner installation to F. and then filtering through a No. 12 Whatman filter paper.

Gel From Burner lnstallation Gel From Burner Separated Gel Installation Appearance Black Gel.

Yellow-Green Gel.

Inspection: Sulfur, Bomb, Percent Mercaptan Sulfur, Percent. Phosphorus, Percent Nitrogen, Percent Water, p.p.m., Karl Fischer Method. pH Value, Glass-Salome] Electrode. Analysis, Spectrographic, p.p.m. Samnil. trace. 361

Aluminum Silicon Ash (Max. Temp. 1,000 F.), Perceut Analylsis, Spectrographic:

lnum

major. trace. trace. trace.

The gel sample from Installation B also indicated the presence of the commercial fuel oil sludge inhibitor employed in the fuel oil. The gel sample from Installation A was not tested for the presence of sludge inhibitor.

With respect to the significant components of the gels, the sulfur content is probably traceable directly or in directly to the sulfur content of the distillate fuel oil. Whether sulfur accelerates or is essential to gel deposition has not been definitely determined. However, it may be significant that the problem of gel deposition has followed the manufacture of distillate fuel oils from crude oils of relatively high sulfur content. The water content of the gels is probably traceable to moisture entrained in the fuel oil, which can be present as a rmult of steam stripping of the fuel oil during distillation of the latter, as a result of contact with residual water in storage tanks or the tanks of marine transport vessels, as a result of condensed moisture from the atmosphere, or as a result of other causes. Experimental evidence indicates that water tends to promote gel formation. The copper present in the gels appears to be traceable to copper fuel feed lines in burner installations or to the ,ism previously identified as a species of Monilia.

eate ie fuel oil gel deposits.

A systematic investigation of a large numberofsamples of fuel oil gels has revealed in every instance the presence of an apparently pure strain of living microorganism, andall available evidence points to these microorganisms as the cause of the fuel oil gels. It is somewhat surprising to find that any microorganism can survive and multiply in the fuel oil, which may account, at least in part, for the apparent purity of the strain. Moreover, it has been found that a 'gel can be produced in incubated samples of previously sterilized fuel oil by inoculation of the fuel oil with a small amount of the gel forrning microorganisms taken from oil burner installations com taining fuel oil gel deposits. It has also been found that the addition of water to the fuel oil appears to promote the development of the gels. Furthermore, when a piece of copper wire is placed in the fuel oil, gel formation appears to be promoted. Gel formation appeared to be especially favored in fueloil samples that had been inoculated with gel-forming microorganisms and that were maintained in contact with both metallic copper and water. containing organic matter capable of supporting microbial life. Whether the fuel oil' gels are produced as such by the microorganims, or whether the microorganisms merely transform fueloil components and/or materials contained therein or contacted thereby to gelforming materials, is not clear. The latter possibility would seem to find some support in the fact that gels resembling those found in the field have been prepared in the laboratory from a mixture of dodecyl and xylyl mercaptans and oil-soluble copper naphthenate.

Under a magnification of 430 times, the fuel oil gelforming microorganisms appear as a mass of multicellular filaments. The filaments show branching, and there is evidence of reproduction by budding. These characteristicsare typical of yeast-like microorganisms.

The exact identity of these gel-forming microorganisms is diflicult to ascertain, and therefore the invention is not limited to any specific scientific class of microorganism. The fuel oil gel-forming microorganisms. may .be a species of sulfur-utilizing tilamentous'bacteriaof the Beggiato aceae family, e.g., Beggiatoa, as might be suggested by the consistent presence of sulfur in the'gels. However, available evidence is conflicting as to whether thefuel oil gel-forming microorganismsthrive in contact with sulfur. The possibility that the gel-forming microorganisms are of the Beggiatoaceae family would appear to be more or less negatived by the fact that these gel-forming microorganisms appear under magnification as multicellular branched Hyphae, and by the fact'that they appear to reproduce by; budding, whichfacts are characteristicof fungi such as Hyphornycetales, such as for "example species of Pullularia or Monilia, i.e., Candida. Photomicrographs of the gel-forming microorganisms show a particularly marked similarity to those of a microorgan- The fact that some strains of the genus Monili-a are known to form mucous or gelatinous masses may besignificant insofar as the present problem is concerned.

In what manner the distillate fuel oilshavebecome infected has not been established because of the. many possible sources of contamination, such as for example contact with residual water instationary storage tanks tion, or merely air. Inthis connection it may be pertinent to note that species of Moniliahave been found as contaminants in air. 7 t v indicated above it has been found that the problem of geldeposition in distillate fuel oils. can be-alleviated,

r or storage tanks of marine transports, decaying vegetal killing the fuel oil gel-forming microorganisms. An eye ample of an excellent anti-microbial agent of the kind included by this invention is n-propyl Formcel which is a commercial bactericide consisting of a 40 percent solution of formaldehyde in n-propyl alcohol. Examples of I other anti-microbial agents that are effective to destroy fuel oil gel-forming microorganisms are n-propyl alcohol and orthophenylphenol (Dowicide 1 Although each of the above disclosed anti-microbial agents is soluble in distillate fuel oil in microbial proportions, the invention is not restricted to the use of oil-soluble anti-microbial agents, and water-soluble, oil-insoluble anti-microbial agents can be used. An example of such an agent is a mixture of alkyltolylmethyl trimethyl ammonium chlc rides containing alkyl groups ranging from C H to C I-I This agent is a commercial anti-microbial agent marketed as a 50 percent aqueous solution under the name Hyamine 2389 by Rohm & Haas. An example of another Water-soluble anti-microbial agent effective to destroy fuel oil gel-forming microorganisms is a mixture of alkyldimethylbenzylammonium' chlorides wherein the alkyl groups are from cgHlq to C18H37. This material is marketed under the name Roccal by the Sterwin Chemical Company. The invention lends itself to the use of water-soluble, oil-insoluble anti-microbial agents in different ways. Thus, the water-soluble anti-microbial agents may be incorporated in the infected fuel oils by the use of dispersing agents, mutual solvents or blending agents that are compatible with the fuel oil and the antimicrobial agent and that do not materially impair the anti-microbial properties of the latter, in an amount sufficient to provide a homogeneous composition. Ex amples of anti-microbial agent-containing concentrates containing blending agents suitable for the purposes of this invention are concentrated solutions containing, for

' example, 10,20 or 35 percent Roccal in acetone, alcohol water. can be added to the water layer in a fuel oil tank.

Nq ma lyt ana usq s. Ph Qt ab 0 w gallons l be found at the bottom of a 2"7- 5 gallon fuel oil tank. The amount of Roccal', Hyarnine 2389 or other watersoluble anti-microbial agent added to the 'tank can be adjusted toprovide the ultimate concentration desired in the; aqueousphase, e .g., 0.01 volume percent or more.

As indicated, the above-specified anti-microbialagents are illustrative only and the present invention is. not restricted to their use, Other anti-microbial agents capable of killing the fuel oil gel-forming microorganisms. can be used. Although the action of the anti-microbial agents upon the gehforming microorganisms with which this in vention is concerned is apparently quite selective, other suitable anti-microbial agents can bedetermined by trial and error, or preferably, by laboratory scale tests. For example cultures of the gel-formingmicroorganisms can be prepared byinoculation' of agar plates, and, after wthyco q i s be om d n u sh b e several drops of h nt -m r b al n ec t be n tested. an. be app i at points on thefagar plate where the colonies appear.

fiThe culture platescan then be incubated at a tempera- H re av a h is w at the. m sm rs'a ismsfe-a. 37 'C.,; and examined for microbial growth after 24 and ,72-hours. If no growth is evident during theseexarnina ti ons' it can .bejassumed that the organisms have beendestroyed, .Fuel oil solutions" containing respectively 0.1

volume Pe n n-rropy am d, nrPrcpfl "8429 an o-phenylphenol, and water solutions containing, resp'eo .tively 0.1 volume percent of Roccal and Hyamine 2389 have proved effective under the conditions of this test. .Ihe addition of small amounts of anti-microbial agents of the type disclosed herein to fuel oils that tend to deposit gels of microbial derivation has been found -to produce excellent results. The anti-microbial agents of this invention should be used in concentrations effective to destroy the gel-forming microorganisms, i.e., in microbicidal proportions. of the anti-microbial agents of this invention may, of course, vary with the nature of the individual agents {themselves and possibly in some instances according to The optimum concentration the degree of infection of the fuel oil by gel-forming microorganisms. Generally speaking, highly effective results will be obtained by addition" to the fuel oil, or

'to aqueous phase material in contact therewith,of anti- ,a relatively less active anti-microbial agent, concentrations of anti-microbial agent in excess of 0.5 volume per- ,cent, for example up to 1.0 volume percent, or possibly more, may be necessary. However, in no instance should the concentration of the additive be so great as to materially impair the ignition or mmbustibility char-..-.

acteristics of the fuel oil.

The anti-microbial agents disclosed herein can be used to treat the distillate fuel oils that tend to deposit gels .ofmicrobial derivation in any suitable manner. For example, oil-soluble anti-microbial agents of the class dis-..

closed herein or in the form of concentrated solutions in compatible solvents, can be added as such, directly to the fuel oils at the refinery. However, because of the fact that gel deposition due to gel-forming microordue to the presence of gel-'fomiing microorganisms. A specific example of a fuel oil, the treatment of which is included by this invention, is No. 2 fuel oil, a type of disillate fuel oil used for domestic heating and light industrial heating purposes. A No. 2 fuel oil is defined in the ASTM Standards on Petroleum Products and Lubricants, under the specification designated D-396-48T. Specific examples of other distillate fuel oils included by the invention are diesel fuels and No. 1 fuel oil. It is noted that the problem of gel formation due to micro-organisms appears to be restricted to distillate fuel oils. The reason for this apparent selectivity is not certain, but it may be due to the charac- "teristi'cally high sulfur content of these fuel oils, or it may be due to the nature of the conditions under which these oils are used. Thus, these oils are normally used in installations involving relatively long term storage in .contact with water and copper.

The terms microbial, anti-microbial," microbicidal" and the like are used herein in their broader sense and as such have reference to microbes or microorganisms broadly, whether or not they are pathogenic.

Fuel oil compositions within the scope of this invention are illustrated by the following specific examples.

EXAMPLE I Gravity: API 13.5 Viscosity SUV: sec., 77 F. 137.9 Flash, 00: F. 132 'Pour: F. Below 70 The relatively small change in the properties of the fuel oil brought about by the use therein of 0.1 volume percent n-propyl Formcel is illustrated by the following inspections:

Uninhibited Fuel Oil Example I Fuel Oil Stock+ Fuel Oil Stock Sludge Composi- Inhibitor tion Make-up, Percent by Volume:

No. 2 Fuel Oil Stock 100 100 100 Inhibitor Added, Percent by Volume- Sludge Inhibitor l 0.02 0.02 n-Propyl Formcel 0.1 Inspections:

Color, ASTM Union l. 75 1. 75 1.75 Stability Test, 210 F., 16 Hrs.

Existent Insoluble Matter, rug/600 g 2 3 1 Potential Insoluble Matter, mg./600 g 3 2 1 Filtrate:

Color, ASTM Union 2. 5 2. 5 2. 6 Oven Storage Stability, After 4 Weeks, 110 F.-

Existent Sludge, rug/500 ml 3 2 2 Flltrate:

Color, ASTM Unlon..-.- 2. 5 2. 5 2. 75 Flash, PM, F 160 146 1 Barium long-chain alkyl benzene sulfonate, 50% oil solution.

ganisms has not proved to be a problem in all burner installations, it may be preferable for the anti-microbial agents to be incorporated in the fuel oil in the tanks of fuel oil retailers, or in the tanks of individual burner installations. When blending agents are employed therewith, oil-insoluble anti-microbial agents can be incorporated into the fuel oil similarly as oil-soluble agents.

' Normally, some agitation is desirable during admixture of the anti-microbial agents with the fuel oil, but this is not, essential. The manner of treatment of fuel oil in the instance of oil-insoluble anti-microbial agents in the ab- "sence of blending agents has been indicated previously.

Fuel oils that can be treated according to this invention are those distillate fuel oils that tend to deposit gels EXAMPLE 11 Another distillate fuel oil composition according to this invention was prepared by incorporation of 0.1 volume percent o-phenylphenol in a No. 2 fuel oil of the kind tending to deposit gels and having the following inspections: 7

- amass EXAMPLEIII treated and prepared according to this inven n by in corporation therein of other anti-microbial agents that are efiective for the purposes of this invention, in the same or equivalent proportions. Forenample, to either of; the b s u l oil omp iti ns. ofv xa pl s 1: nd ther canvbe added 0.1 volume percent Roccal or Hyamine 2389v in a blending agent of the kind described previously.

By way of further illustrating the efiectiveness of this invention in combating fuel oil gels. itcan be noted that 8 forming microorganisms found present, nor was there any evidence of new gel formation in these installations. In some cases where some or all of the gel was purpose? 1y left intact, the gel was found to be reduced inquantity or eliminated. One of the untreated installations which at the first visit had contained. no. gel but which contained gel-forming microorganisms was found to have developed the gel during 45' days elapsed between visits. A second o -o n inina un reat d. n tall tion ta t d v lop l n 14 ys, but. still c ntained. g lr orm ng mi oorganisms after this period; A third non-gel-containing in tall tion wh h ad. been ea e h n-pr py Fo mo as d. to .h enose d p s s or lrf rmi g m organisms after 15 days. In the table following there are presented the test results obtained several indiidu ns n s. cons dere mo e or l ss eprese tat e of the entire test.

Table A InltlalVlslt.

Gel Mlcro- Method Fuel Gil Organisms of No. Sample in System Treat-.- Comments Quantity Nature ment 1,... Heavy.-. Film At Bumer.. Positive-.. A Gel removed from flow valve and screen.

None n r 3,. Medium... Eilm A]: Burner. Positive..- A Gel'leit on flow valve and screen and level valve. 4 Heavy Bead.... do.,.. .,i .,d 0--.-.--- A Gel removed from flow valve screen and copper. 6.. ...do Fibrous.-- '.....do ...do E B Qelrernovedtrqmpnmpstrainer. 6 n 1 Read do n 0 Gelblown irom line. 7 dn rin do do 1) D0, J

1 Second Visit Gel Micro- No. Days. Fuel Oil Sample Organisms Comments.

E a d System Quantity Nature 21 None At'Burner Negatlvo N 0, New Gel. 45 Trace--- At Const. Level New Gel.

Valve. 24 None... None do No New Gel. 13 -do At Burner Negative Do. 15 Trace... Flbr0us. do .do Gel appeared to be 11100111- pletely removed original ge 13 None, No New Gel. 13 Trans... Gel appeared to be incompltletely removed original a. full scale test was carried out involving a number of actual burner installations using No. 2 fuel oil and known or suspected to have a problem duetogel deposits. Oi;

. the total installations involved in the test complete results were obtained on 26 burner iustallationsdivided among several relatively widely separated geographical areas. At the outset of the investigation, samples of fuel gel-forming microorganisms. Gel deposits, occurring in the form of films, beads, or fibers, in the order of prevalence named, were found in 23 of the 26 installations ;and' the volume of gel found was rated'as trace, light,

medium; or heavy. All of the installations in which gel was found, were; treated n:propy1 Formcel in the proportion of about 0.1 volume percent," insome instances with and in others without agitation. In most instances to about 4 5 days, the sa me 26 installations were again checked for gel, and fuel oil samples -were again taken for microscopic examination. In none of-the 23 installations-where the n-propyl -=Forrncel wasadded were geloil were taken from 25 of these 26 installations and upon 1 microscopic examination, each sample proved to contain In the foregoing table under the column headed Method of Treatment, the letter entries have the following meanings:

" A, agent added through fill line without agitation.

B, agent added through fill line; agitation obtained by fuel delivery. Y

C, agent added through fill line; agitated by hand.

D, agent blown through feed line into tank and agitated.

. visit and no anti-microbial agent was employed. Entries opposite No. 3 in the foregoing tableill trat 1 1- ment of; an: installation where the gel found in thesystern was lefit int-act. Entries opposite No. 4 -in the foregoing table illustrate treatment of an installation containing bead l-ike, gel deposits. Entries'opposite No.5 in the foregoing table are illustrative of treatment of an 7 installation containing fibrous. gel deposits, using a difier- Lent method ofiintroducing; the. an .orobhlassu Entries opposite No. 6 and No. 7 in the foregoing table are illustrative of treatment of installation using still other methods of introducing the anti-microbial agent.

If desired, the fuel oil compositions of this invention may contain, in addition to the compounds previously discussed, oxidation inhibitors, flash point control agents, corrosion inhibitors, antifoam agents, ignition quality improvers, combustion improvers, other sludge inhibitors, and other additives adapated to improve the oils in one or more respects.

Obviously many modifications of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A fuel oil composition comprising a major proportion of a distillate fuel oil in contact with an aqueous phase and tending to deposit gels that contain water, sulfur and copper, due to the presence in at least one of said oil and said aqueous phase of microorganisms that promote deposition of such gels, and a microbicidal amount of an anti-microbial agent that is effective to destroy said gel-promoting microorganisms.

2. The fuel oil composition of claim 1 wherein said microbicidal amount is about 0.01 to about 1.0 volume percent of the composition.

3. The fuel oil composition of claim 1 wherein said microbicidal amount is about 0.05 to about 0.5 volume percent of the composition.

4. A fuel oil composition comprising a major proportion of a distillate fuel oil in contact with an aqueous phase and tending to deposit gels that contain water, sulfur and copper, due to the presence in at least one of said oil and said aqueous phase of microorganisms that promote deposition of such gels, and a microbicidal amount of an anti-microbial agent effective to destroy said gel-promoting microorganisms, said anti-microbial agent being selected from the group consisting of n-propyl alcohol, a 40 percent solution of formaldehyde in n-propyl alcohol, o-phenylphenol, mixed alkyltolylmethyl trirnethyl ammonium chlorides whose alkyl groups contain 9 to 15 carbon atoms, and mixed alkyldimethylbenzylammonium chlorides whose alkyl groups contain 8 to 18 carbon atoms.

5. A fuel oil composition comprising a major proportion of a distillate fuel oil in contact with an aqueous phase and that tends to deposit gels that contain water, sulfur and copper, due to the presence in at least one of said oil and said aqueous phase of microorganisms that promote deposition of such gels, and a microbicidal amount of a 40 percent solution of formaldehyde in n-propyl alcohol.

6. A fuel oil composition comprising a major proportion of a distillate fuel oil in contact with an aqueous phase and that tends to deposit gels that contain water, sulfur and copper, due to the presence in at least one of said oil and said aqueous phase of microorganisms that promote deposition of such gels, and a microbicidal amount of n-propyl alcohol.

7. A fuel oil composition comprising a major proportion of a distillate fuel oil in contact with an aqueous phase and that ends to deposit gels that contain water, sulfur and copper, due to the presence in at least one of said oil and said aqueous phase of microorganisms that promote deposition of such gels, and a microbicidal amount of o-phenylphenol.

8. A fuel oil composition comprising a major proportion of a distillate fuel oil in contact with an aqueous phase and that tends to deposit gels that contain water, sulfur and copper, due to the presence in at least one of said oil and said aqueous phase of microorganisms that promote deposition of such gels, and a microbicidal amount of mixed alkyltolylmethyl trimethyl ammonium chlorides whose alkyl groups contain 9 to 15 carbon atoms.

9. A fuel oil composition comprising a major proportion of a distillate fuel oil in contact with an aqueous phase and that tends to deposit gels that contain water, sulfur and copper, due to the presence in at least one of said oil and said aqueous phase of microorganisms that promote deposition of such gels, and a microbicidal amount of mixed alkyldimethylbenzyl-ammonium chlorides whose alkyl groups contain 8 to 18 carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS 1,987,228 Bruson Ian. 8, 1935 2,097,085 Fabian et al. Oct. 26, 1937 2,680,058 Harris et a1. June 1, 1954 2,709,665 Campbell et al. May 31, 1955 OTHER REFERENCES Journal of Bacteriology, Vol. 41, 1941, The Utilization of Certain Hydrocarbons by Microorganisms, by Bushnell et al., pages 671 and 672, complete article, pages 653-673.

Deodorant and Germicidal Detergents, by Hart et al., Manufacturing Chemist, April 1951, pages 143- 146.

Reprint, from Bacteriological Reviews, Vol. 18, No. 4, December 1954, Microbiology in the Petroleum Industry, by Davis et al., pages 230 and 233, complete article, pages 215-238.

,7 77 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent N0 2,975 O42 March 14, 1961 Claude R Summers Jr.

It is hereby certified'that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 4, line 1O for "microbial" read microbicidal column 1O line 10, for "ends" read tends Signed and sealed this 25th day of July 1961.,

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent N0}. 2,975,042 4 March 14, 1961 Claude R, Summers, Jr.

It is hereby certifiedthat error appears, in the vabove numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 10, for "microbial" read microbicidalcolumn 10, line 10, for "ends" readtends Signed and sealed this 25th day of July 1961.

(SEAL) Attest:

ERNEST W. SWIDER 7 DAVID L. LADD Attesting Officer Commissioner of Patents 

1. A FUEL OIL COMPOSITION COMPRISING A MAJOR PROPORTION OF A DISTILLATE FUEL OIL IN CONTRACT WITH AN AQEUOUS PHASE AND TENDING TO DEPOSIT GELS THAT CONTAIN WATER, SULFUR AND COPPER, DUE TO THE PRESENCE IN AT LEAST ONE OF SAID OIL AND SAID AQUEOUS PHASE OF MICROOGRANISMS THAT PROMOTE DEPOSITION OF SUCH GELS, AND A MICROBICIDAL AMOUNT OF AN ANTI-MICROBIAL AGENT THAT IS EFFECTIVE TO DESTROY SAID GEL-PROMOTING MICROOGANISMS. 